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01 740iL, 99 Z28, 06 SRX V8 rwd
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Discussion Starter #1
Wondering what others thoughts are on this. FE3/F55 SRX, so it has stiffer FE3 springs and F55 magnetic ride shocks, and the rear magnetic ride shocks have the air compressor powered self leveling function. The air bellows on the rear shocks are torn, and the compressor no longer turns on. However, like some others have reported when their compressors cease functioning, there are no error messages appearing on the drivers information center. A couple of the magnetic ride shocks are now seeping, and now ride quality has begun to be affected - which is the reason I'm fixing it. No error messages associated with the seeping shocks either - only when I unplug a shock do I get one, then it's the "speed limit 80 (or is it 85?)" message.

If it was just the shocks, I'd be somewhat tempted to replace with stock F55s even with $. But given my non running compressor, I'd likely need a new part there as well or else my fancy new F55 shocks, at least at the rear, wouldn't function at a level that would be worth the $. And the additional cost for the compressor puts this over the threshold for $ = Benefit.

I looked at an aftermarket F55/Air replacement setup, like Strutmasters, Suncore or Suspension Discount Warehouse on ebay. But reviews are hard to come by for any of these systems on an SRX, and it's hard to tell what brand of shocks they are using - which concerns me given the impact shocks have on ride quality, and the differences in longevity between no name shocks on one end and Sachs, Koni, Bilstein on the other end. Hat to go through an install only to be unsatisfied with the ride or have to re-do it again in short order.

So I'm looking at AC Delco FE1 shocks, front and rear, with the existing FE3 springs. The rears are sachs nivomat, which will provide a self leveling function without the need for a functioning air compressor. I've ordered some resistors and I'll be test wiring one in on a front shock to see if the resistor successfully avoids the speed limit message.

The only question mark I have is how the FE3 springs will play with the FE1 shocks. On the front, I assume the FE3 springs are stiffer than FE1 springs. On the rear, they might be stiffer, but they might be softer - depends on how much the FE3/F55 setup relies on air v. spring rate for leveling. Mine are likely softer than they were when they were new due to age and 90,000 miles. But I'm also figuring that the leap from Fe1 to FE3 cant be that big since all first gen SRXs ive driven ride/handle in a similar fashion regardless of suspension option, and we're talking two different OE springs, not OE v. aftermarket performance springs.

Thoughts?
 

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05 srx awd v6 (gone), '07 GXP, 2010 li'l red wagon 3.6
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For starters, just because there are no DIC messages doesn't mean there are no codes. Have your codes read with a tool that will show ABS codes; then you'll have a good starting point.
 

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01 740iL, 99 Z28, 06 SRX V8 rwd
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Discussion Starter #3
The only suspension related codes I'm concerned about are ones that would put a visual indicator of a code in the cabin(error light or DIC error message) and ones that would inhibit vehicle operation, for example the speed limiter that comes on if you unplug an F55 shock - I've got my resistors from eBay that ought to take care of that one but I'll be confirming with some testing this week.

If the compressor has been non functional for over a year, and it's not yet produced an error light or message, or a code that inhibits vehicle operation, I'm thinking it's unlikely to change course at this point. So I don't plan to touch the compressor or even give it a sideways glance.

Really just curious what folks think about how the FE3 springs will work with the FE1 shocks.
 

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SRX'05 4.6L
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I have that setup you described and I am very comfortable with the choice I made. But I am not a frequent racer and/or drifter. The car still controls much better than most smaller cars I tried driving from relatives.
 

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01 740iL, 99 Z28, 06 SRX V8 rwd
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Discussion Starter #6
@Kipp - it doesn't look like Suncore actually has those in stock - at least they won't let you put one in your cart, instead they give a message that says "Remanufactured Suspension Compressor - insufficient inventory to change quantity."
 

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01 740iL, 99 Z28, 06 SRX V8 rwd
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Discussion Starter #7
Update: Success! New Delphi FE1 shocks all around, plus 3 ohm 50 watt resistors at each corner spliced into the wires that formerly led to the F55 shocks. No error message, rides like new, and still handles well too - comfortable controlled ride. I'm sure I did give up some edge of the performance envelope handling but it doesn't feel like any kind of compromise from behind the wheel. Loading up for a trip in a few weeks, will report back on how the sachs nivomat self leveling function compares to the original air self leveling. In any event it will certainly be better than non functional compressor + torn airbags self leveling ;-)
 

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01 740iL, 99 Z28, 06 SRX V8 rwd
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Discussion Starter #8
Update- loaded the car with a full cago area and 2nd row including an ice chest, dog and kids. Self leveling works perfectly - ride and handling quality remains the same and the rear maintains the unladen height.
 

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01 740iL, 99 Z28, 06 SRX V8 rwd
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Discussion Starter #10 (Edited)
My compressor is present but not functional - still wired in but doesn't turn on and has been that way for some time. The FE1 shocks have a self leveling function that doesn't require air - it's the Sachs Nivomat system that keeps the rear level by using the energy of the natural up and down movement of the suspension to power a pump inside the shock.
 

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01 740iL, 99 Z28, 06 SRX V8 rwd
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Discussion Starter #12
I used AC Delco 540521 for the rear, 540598 for the front. I believe those are the AC Delco part numbers - they may or may not match up with the part numbers in the GM Parts catalog.
 

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SRX V8 AWD
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Thanks. I will try to do the same with mine. Is it necessary to put resistors to each shock or just to rear ones?
 

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01 740iL, 99 Z28, 06 SRX V8 rwd
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Discussion Starter #14
I was converting all four corners from magnetic ride to FE1 shocks, so I needed the resistors on all four corners.
 

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05 Stealth Gray CTS-V, 08 Light Platinum SRX V8, 05 White Diamond STS4 V8 1SG
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Yeah those Nivomat shocks really work well. I have an FE1 08 with them and they just work. I also have them on my CTS-V (standard) and they work perfectly there, as well. Almost makes you wonder why any OEM bothers with bulky and complicated air systems for leveling.

Slightly off topic though: do all F55 SRXs have FE3? My 08 has the sport package which ironically locks you out of F55 and is also mandatory FE1. Just curious.
 

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01 740iL, 99 Z28, 06 SRX V8 rwd
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Discussion Starter #18
I got them from Hong Kong via eBay. The seller was "electronics-salon"
 

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SRX V8 AWD
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I've done swap few weeks ago and I am happy with the result. Vehicle rides in a different way - suspension is a bit harder but I personally like it.
At first I did not put any resistors and got that message and speed limit. I also had problems with finding proper resistor locally so I ordered online. I did front shocks for now only and resistor installation was easy as these cables are located under the hood.
So I can confirm that changing from MRC to gas shocks works :)
 

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I used AC Delco 540521 for the rear, 540598 for the front. I believe those are the AC Delco part numbers - they may or may not match up with the part numbers in the GM Parts catalog.
TTopJohn, I too am looking at the same issue you apparently have solved. A few questions: you chose the AC Delco 540521 for the rear - does this shock have the self leveling feature of Nivomat? I ask, because my 06 SRX has HID headlights and wish to preserve the self-level advantage. Is there a reason you didn't go with the Sachs Nivomat set up for the rear?

Also, since its been several months, what has your experience been? Any codes or suspension service indicators? Is the ride similar, worse or better than the factory MRC set up? Did you notice anything lacking in spring rate? As you pointed out in your messages, you kept the factory FE3 springs and only change the shocks. So if i understand this correctly, you're running Sport Springs (the ones that came from the factory - FE3) and the soft ride FE1 shock. Doesn't sound like a bad set up, but would appreciate some seat of the pants perspective.

Thanks in advance.
 
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